Figure 6. LSPC delivery to PrP^C-expressing cells in vivo.

FVB mice were intravenously injected with liposomes alone (panels a–e) or LSPCs containing DyLight 488-labeled peptides and Alexa 488-labeled siRNAs as follows: PrP-RVM-9r (f–j), Control-RVG-9r (k–o), or PrP-RVG-9r (p–t). Mice were sacrificed 24 hours later, dissected, and their brains snap frozen and 8 µm sections thereof stained with DyLight 649-labeled anti-PrP antibody (a, f, k and p) and DAPI (c, h, m and r) and visualized by fluorescence microscopy. Panels d, f, m and s are labeled to show the granular and (g) molecular (m) layers and white matter tracts (w), Panels e, j, o and t depict magnifications of the granular layer and white matter boundary in the boxed areas in panels d, i, n and s. Inset in panel p depicts a serial section stained with an irrelevant isotype control antibody. Scale bars, 50 µm for all panels except e, j, o and t, which is 10 µm. (u and v) FACS analysis of PrP-RVG-9r LSPC delivery to brain cells (checkered peak (u) and circle (v)), kidney cells (white peak and circle), splenocytes (dark grey peak and triangle) and hepatocytes (black peak and square). The light grey peak (u) and square (v) depict PBS-treated, unstained control brain cells. (w and x) FACS analysis of PrP^C expression on brain cells treated with PrP-RVG-9r (red dots (w) and circle (x)), RVG-9r-control (green dots and circle), PrP-RVM-9r (blue dots and triangle) LSPCs, or liposomes alone (black dos and square). The grey dots and square depict untreated, unstained brain cells. (y) Cumulative data showing relative PrP expression on brain cells treated with liposomes alone (grey bar) or with LSPCs containing PrP-RVM-9r (blue), control-RVG-9r (green) or PrP-RVG-9r (red). Symbols associated with each bar indicate values for individual mice.